Esteban Alonso-González

Centre National d’Etudes Spatiales | CNES · Centre d’Etudes Spatiales de la Biosphère

The assimilation of data from Earth observation satellites into numerical models is considered to be the path forward to estimate snow cover distribution in mountain catchments, providing accurate information on the mountainous snow water equivalent (SWE). The land surface temperature (LST) can be observed from space, but its potential to improve S...

Monitoring the snowpack remains challenging in part due to the limited availability of observations. On the one hand, the deployment of dense ground-based monitoring networks is hampered by logistical hurdles. On the other hand, satellite-based remote sensing products provide only partial information about the snowpack, often limited to snow-covere...

The Aneto glacier, although it may be considered a very small glacier (<0.5 km2), is the largest glacier in the Pyrenees. Its surface and thickness loss have been continuous in recent decades, and there have been signs of accelerated melting in recent years. In this study, thickness and surface losses of the Aneto glacier from 1981 to 2022 are inve...

Plain Language Summary The monitoring of the seasonal snowpack is important to understand and predict the dynamics of the hydrological and ecological processes, but its continuous monitoring is still a scientific challenge. Particularly in relation to the Snow Water Equivalent (SWE). The available technologies to monitor the SWE exhibit a number of...

It is a widespread assumption that burned area and severity are increasing worldwide due to climate change. This issue has motivated former analysis based on satellite imagery, revealing a decreasing trend in global burned areas. However, few studies have addressed burn severity trends, rarely relating them to climate variables, and none of them at...

Keywords: degree day model, data assimilation, transfer function model, soil surface temperature,climate change The Kulingdakan watershed is located in East Siberian region and has been studied and monitored for about two decades. It is located 5 km away from Tura city (64°17’ N, 100°13’E), where daily meteorological data (temperatures, snow heigh...

Despite the important hydrological and ecological implications of the snowpack, its real time monitoring remains challenging. This is particularly relevant in relation to the Snow Water Equivalent (SWE), as the available technologies which measure it, exhibit a number of limitations that difficults their operational implementation. In this work, we...

The Mediterranean Basin has experienced one of the highest warming rates on earth during the last few decades, and climate projections predict water scarcity in the future. Mid-latitude Mediterranean mountain areas, such as the Pyrenees, play a key role in the hydrological resources for the highly populated lowland areas. However, there are still l...

Climate warming is changing the magnitude, timing, and spatial patterns of mountain snowpacks. A warmer atmosphere may also lead to precipitation phase shifts, with decreased snowfall fraction (Sf). The combination of Sf and snowpack decreases directly affects the frequency and intensity of rain-on-snow (ROS) events, a common cause of flash-flood e...

The Aneto Glacier, although it may be considered very small (<0.5 km2), is the largest glacier in the Pyrenees. Its shrinkage and wastage have been continuous in recent decades, and there are signs of accelerated melting in recent years. In this study, changes in the area and volume of the Aneto Glacier from 1981 to 2022 are investigated using hist...

Accurate knowledge of the seasonal snow distribution is vital in several domains including ecology, water resources management, and tourism. Current spaceborne sensors provide a useful but incomplete description of the snow-pack. Many studies suggest that the assimilation of remotely sensed products in physically based snowpack models is a promisin...

The assimilation of data from Earth observation satellites into numerical models is considered as the path forward to estimate SWE distribution in mountain catchments. The land surface temperature (LST) can be observed from space, but its potential to improve SWE simulations remains underexplored. This is likely due to the insufficient temporal or...

Snow observations are important in many mountain areas to quantify the water stored in snowpacks and to predicting runoff during the melting period. In this study we compare the performance of five different regional-scale gridded snow products to reproduce snow water equivalent (SWE) in the Upper Euphrates region (Karasu Basin, 10,275 km2), with o...

In mountain areas, the phenology and productivity of grassland are closely related to snow dynamics. However, the influence that snow melt timing has on grassland growing still needs further attention for a full understanding, particularly at high spatial resolution. Aiming to reduce this knowledge gap, this work exploits 1 m resolution snow depth...

The Mediterranean basin has experienced one of the highest warming rates on Earth over the last decades and climate projections anticipate water-scarcity future scenarios. Mid-latitude Mediterranean mountain areas such as the Pyrenees play a key role in the hydrological resources for intensely populated lowland areas. However, there are still large...

Accurate knowledge of the seasonal snow distribution is vital in several domains including ecology, water resources management, and tourism. Current spaceborne sensors provide a useful but incomplete description of the snowpack. Many studies suggest that the assimilation of remotely sensed products in physically based snowpack models is a promising...

This study extends knowledge of the evolution of glacier shrinkage in the Cocuy‐Güican Mountains since the maximum glacier extent of the Little Ice Age (LIA). Mass balance data for the Ritacuba Glacier since 2009 was acquired and compared with available data for the Conejeras Glacier (Los Nevados National Park). This study also investigated the hyd...

This study updates information on the evolution of glacier shrinkage in Cocuy-Güican mountains since the maximum glacier extent of the Little Ice Age (LIA), and presents the first mass balance data of Ritacuba glacier since 2009, that is compared to the available mass balance for the Conejeras Glacier (Los Nevados National Park). This study also di...

The duration of the seasonal snowpack determines numerous aspects of the water cycle, ecology and the economy in cold and mountainous regions, and is a balance between the magnitude of accumulated snow and the rate of melt. The contribution of each component has not been well quantified under contrasting topography and climatological conditions alt...

Understanding those processes in which snow dynamics has a significant influence requires long-term and high spatio-temporal resolution observations. While new optical space-borne sensors overcome many previous snow cover monitoring limitations, their short temporal length limits their application in climatological studies. This work describes and...

In 2015, a new automatic weather station (AWS) was installed in a high elevation site in Gredos mountains (Central System, Spain). Since then, a surprisingly high number of heavy precipitation events have been recorded (55 days with precipitation over 50 mm, and a maximum daily precipitation of 446.9 mm), making this site a hotspot in Spain in term...

Pyrenean glaciers are the largest in southern Europe. Their survival is threatened by climate change, highlighting the significance of their study. This research presents an assessment of changes in the glacierized area and thickness of Pyrenean glaciers from 2011 to 2020, using high-resolution optical satellite, airborne lidar and UAV images. The...

Rain-on-snow (ROS) events can trigger severe floods in mountain regions. There is high uncertainty about how the frequency of ROS events (ROS) and associated floods will change as climate warms. Previous research has found considerable spatial variability in ROS responses to climate change. Detailed global assessments have not been conducted. Here,...

Permafrost is a relevant component of the Pyrenean high mountains, triggering a wide range of geomorphological cryogenic processes. Although in the past decades there has been an increase in frozen ground studies in the Pyrenees, there are no specific studies about rock wall permafrost, its presence, distribution, thermal regime, or historical evol...

The snowpack over the Mediterranean mountains constitutes a key water resource for the downstream populations. However, its dynamics have not been studied in detail yet in many areas, mostly because of the scarcity of snowpack observations. In this work, we present a characterization of the snowpack over the two mountain ranges of Lebanon. To obtai...

Unmanned Aerial Vehicles (UAVs) offer great flexibility in acquiring images in inaccessible study areas, which are then processed with stereo-matching techniques through Structure-from-Motion (SfM) algorithms. This procedure allows generating high spatial resolution 3D point clouds. The high accuracy of these 3D models allows the production of deta...

Recent developments in unmanned aerial vehicles (UAV) and structure from motion (SfM) algorithms have shown reliable results for retrieving snow depth distribution. However, their ability to obtain accurate results usually relies on deploying and measuring the exact position of ground control points (GCP) for georeferencing the information. Commerc...

To make advances in the fire discipline, as well as in the study of CO2 emissions, it is of great interest to develop a global database with estimators of the degree of biomass consumed by fire, which is defined as burn severity. In this work we present the first global burn severity database (MOSEV database), which is based on Moderate Resolution...

Mountain glaciers have generally experienced an accelerated retreat over the last 3 decades as a rapid response to current global warming. However, the response to previous warm periods in the Holocene is not well-described for glaciers of the southern Europe mountain ranges, such as the Pyrenees. The situation during the Medieval Climate Anomaly (...

To advance in the fire discipline as well as in the study of CO2 emissions it is of great interest to develop a global database with estimators of the degree of biomass consumed by fire, which is defined as burn severity. In this work we present the first global burn severity database (MOSEV database), which is based on Moderate Resolution Imaging...

Climate warming will reduce the duration of mountain snowpacks and spring runoff, impacting the timing, volume, reliability, and sources of water supplies to mountain headwaters of rivers that support a large proportion of humanity. It is often assumed that snow hydrology will change in proportion to climate warming, but this oversimplifies the com...

First global burn sevrerity database

Snow dynamics are key to understanding tree growth in mountain forests and future response to climate change. However, precise monitoring of microclimate conditions and variables related to tree growth and functioning are lacking. To advance on those issues, snow cover and microclimate conditions, tree phenology, xylogenesis, intra- annual radial g...

The aim of this work is to understand aerosol transfers to the snowpack in the Spanish Pyrenees (Southern Europe) by determining their episodic mass-loading and composition, and to retrieve their regional impacts regarding optical properties and modification of snow melting. Regular aerosol monitoring has been performed during three consecutive yea...

The Sierra Nevada of Santa Marta (12ºN) hosts a unique glaciated environment (6.5 km²) only 40 km distant from the Caribbean Sea. However, the remoteness of the glaciers and restricted access to the region has so far prevented onsite field work research from being undertaken. We worked with several very high resolution airborne and satellite images...

The snowpack over the Mediterranean mountains constitutes a key water resource for the downstream populations. However, its dynamics have not been studied in detail yet in many areas, mostly because of the scarcity of snowpack observations. In this work, we present a characterization of the snowpack over the two mountain ranges of Lebanon. To obtai...

The snow dynamics in alpine systems play a significant role in the hydrosphere, biosphere, and anthroposphere interfaces of these regions. The storage of water resources as snow is essential for ecosystems, human consumption, tourism, and hydropower in many areas. However, snow data are usually scarce due to poor accessibility, difficulties to main...

Air temperature changes as a function of elevation were analyzed in a valley of the Spanish Pyrenees. We analyzed insolation, topography and meteorological conditions in order to understand how complex topoclimatic environments develop. Clustering techniques were used to define vertical patterns of air temperature covering more than 1000 m of verti...

Mountain glaciers have generally experienced an accelerated retreat over the last three decades as a rapid response to current global warming. However, the response to previous warm periods in the Holocene is not well-described for glaciers of the of southern Europe mountain ranges, such as the Pyrenees. The situation during the Medieval Climate An...

Seasonally frozen ground, mountain permafrost and cryogenic geomorphological processes are important components of the Pyrenean high mountains. This work presents the results of a study on the distribution of frozen ground in a marginal and paraglacial environment of temperate mountains. An inventory was made of landforms and indicators of frozen g...

Image network geometry, including the number and orientation of images, impacts the error, coverage, and processing time of 3‐D terrain mapping performed using Structure‐from‐Motion and MultiView‐Stereo (SfM‐MVS). Few studies have quantified tradeoffs in error and processing time or ways to optimize image acquisition in diverse topographic conditio...

Manually collected snow data are often considered as ground truth for many applications such as climatological or hydrological studies. However, there are many sources of uncertainty that are not quantified in detail. For the determination of water equivalent of snow cover (SWE), different snow core samplers and scales are used, but they are all ba...

To know the vertical distribution of air temperature is complex, and this is necessary for different applications. The main explanatory variable of air temperature is elevation above sea level, whose relationship with air temperature is measured by air temperature lapse rates (LRs). LRs can vary considerably spatiotemporally due to a wide spectrum...

In this study we investigated the sensitivity of the snowpack to increased temperature and short-wave radiation, and precipitation change along an elevation gradient (1500–2500 m a.s.l.) over the main mountain ranges of the Iberian Peninsula (Cantabrian Range, Central Range, Iberian Range, Pyrenees, and the Sierra Nevada). The output of a meso-atmo...

This study investigated the temporal variability and changes in snow cover duration and the average snow depth from December to April in the Pyrenees at 1500 and 2100 m a.s.l. for the period 1958‐2017. This is the first such analysis for the entire mountain range using SAFRAN‐Crocus simulations run for this specific purpose. The SAFRAN‐Crocus simul...

Snowpacks and forests have complex interactions throughout the large range of altitudes where they co‐occur. However, there are no reliable data on the spatial and temporal interactions of forests with snowpacks, such as those that occur in nearby areas that have different environmental conditions and those that occur during different snow seasons....

The North Atlantic Oscillation (NAO) is considered to be the main atmospheric factor explaining the winter climate and snow evolution over much of the Northern Hemisphere. However, the absence of long-term snow data in mountain regions has prevented full assessment of the impact of the NAO at the regional scales, where data are limited. In this stu...

Spain, one of the most mountainous countries in Europe, suffers from frequent river flooding due to specific climatic and topographic features. Many headwaters of the largest rivers in Spain are located in mountainous areas of mid-to-high elevation. These include the Pyrenees, the Central System, and the Cantabrian mountains, that have a sustained...

Glaciers in Peru play a major role in water availability and they also have direct implications on natural hazards such as glacial lake outburst floods (GLOFs) and/or ice avalanches, which have caused a high number of fatalities and damage to infrastructure in the last decades. Despite a noticeable effort to quantify and understand the shrinking an...

Climate warming is responsible for observed reduction in snowpack depth and an earlier and faster melt-out in many mountains of the Northern Hemisphere. Such changes in mountain hydroclimate could negatively affect productivity and tree growth in high-elevation forests, but few studies have investigated how and where recent warming trends and chang...

Acquiring information on snow depth distribution at high spatial and temporal resolution in mountain areas is time consuming and generally these acquisitions are subjected to meteorological constrains. This work presents a simple approach to assess snow depth distribution from automatically observed snow variables and a pre-existing database of sno...

The presence of a seasonal snowpack determines the hydrology, geomorphology and ecology of wide parts of the Iberian Peninsula, with strong implications for the economy, transport and risk management. Thus, reliable information on snow is necessary from a scientific and operational point of view. This is the case of the Iberian Peninsula where, lac...

A set of 17 air temperature and relative humidity sensors were used to analyze the temporal variability of surface air temperature (Tair), wet bulb temperature (Twb), and daily snowmaking hours (SM, number of hours per day with Twb < − 2 °C), lapse rates, and the occurrence of thermal inversions at the Formigal ski resort (Spanish Pyrenees) from De...

This work combines very detailed measurements from terrestrial laser scanner (TLS), ground-based interferometry radar (GB-SAR) and ground-penetrating radar (GPR) to diagnose current conditions and to analyse the recent evolution of the Monte Perdido Glacier in the Spanish Pyrenees from 2011 to 2017. Thus, this is currently one of the best monitored...

Recently, a homogeneous database has been generated to study the spatial-temporal dynamics of the snow cover in the Spanish peninsular territory, from remote sensing (AVHRR-NOAA and MODIS) and energy balance models (WRF-FSM). These data series used at regional scale show the uncertainty of their application in small headwaters to better understand...

In recent years different remote sensing techniques have been proved to be very useful for snow measurement and monitoring in alpine environments. Terrestrial Laser Scanner has been tested in different environments and conditions and presented a remarkable performance and accuracy to measure spacial and temporal distribution of snow depth at differ...

Structure-from-Motion (SfM) photogrammetry is one of the most common approaches used to elaborate high-resolution Digital Elevation Models (DEMs) nowadays. Factors that influence the final error associated to the derived DEM are: camera-to-ground distance, camera-sensor system parameters, image network geometry, matching performance, terrain type,...

Structure-from-Motion (SfM) photogrammetry is one of the most common approaches used to elaborate high-resolution Digital Elevation Models (DEMs) nowadays. Factors that influence the final error associated to the derived DEM are: camera-to-ground distance, camera-sensor system parameters, image network geometry, matching performance, terrain type,...

Although the mean environmental lapse rate (MELR) value (a linear decrease of − 6.5 °C/km) is the most widely used, near‐surface (i.e., non‐free atmosphere) air temperature lapse rates (NSLRs; measured at ~1.5 m height) are variable in space and time because of their dependence on topography and meteorological conditions. In this study we conducted...

We present snow observations and a validated daily gridded snowpack dataset that was simulated from downscaled reanalysis of data for the Iberian Peninsula. The Iberian Peninsula has long-lasting seasonal snowpacks in its different mountain ranges, and winter snowfall occurs in most of its area. However, there are only limited direct observations o...

This work describes the snow and meteorological data set available for the Izas Experimental Catchment in the Central Spanish Pyrenees, from the 2011 to 2017 snow seasons. The experimental site is located on the southern side of the Pyrenees between 2000 and 2300 m above sea level, covering an area of 55 ha. The site is a good example of a subalpin...

We present snow observations and a validated daily gridded snowpack dataset that was simulated from downscaled reanalysis of data for the Iberian Peninsula. The Iberian Peninsula has long-lasting seasonal snowpacks in its different mountain ranges, and winter snowfalls occur in most of its area. However, there are only limited direct observations o...